From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3989CC32751 for ; Wed, 7 Aug 2019 20:58:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 105822184E for ; Wed, 7 Aug 2019 20:58:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565211526; bh=BHNLhewizLMLp7YbdvNCnIzAyhkg8YnrouHHCEfoVa4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=wlc1kIrDnXgMIsFVvJwlHEqCX389zPf4JHK8eP6u2o/rOZn4FGbc1uxNaQqxBmSuW JCdETcwWVc+arwdCGXlriJolVR5x40MG8KNndtbNDd9222M69P1eWq7HbxvjmaWcfg HI8kBK7axPsk93l5Vw4Xi7KR7Kw4oLASZIbD17wY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389082AbfHGU6m (ORCPT ); Wed, 7 Aug 2019 16:58:42 -0400 Received: from mail.kernel.org ([198.145.29.99]:58456 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729714AbfHGU6m (ORCPT ); Wed, 7 Aug 2019 16:58:42 -0400 Received: from akpm3.svl.corp.google.com (unknown [104.133.8.65]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8357A2173C; Wed, 7 Aug 2019 20:58:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565211521; bh=BHNLhewizLMLp7YbdvNCnIzAyhkg8YnrouHHCEfoVa4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=u8sRhP8bK815tFw7ifhBS4SB17zcgKZ47zrUXrczJIScpe3WeCh14v/46lx0CCeRW 0rylwHRSL91S/Vbfj1YBHXKkOsfP1dbUn9GG5ygIrbrkQElQQjhhVbQw/U11jkcUcy /6UT11ZTtKTBTxqWUlh1WwFRaVjP4y6LQYMuaHYg= Date: Wed, 7 Aug 2019 13:58:40 -0700 From: Andrew Morton To: Joel Fernandes Cc: linux-kernel@vger.kernel.org, Alexey Dobriyan , Borislav Petkov , Brendan Gregg , Catalin Marinas , Christian Hansen , dancol@google.com, fmayer@google.com, "H. Peter Anvin" , Ingo Molnar , Jonathan Corbet , Kees Cook , kernel-team@android.com, linux-api@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Michal Hocko , Mike Rapoport , minchan@kernel.org, namhyung@google.com, paulmck@linux.ibm.com, Robin Murphy , Roman Gushchin , Stephen Rothwell , surenb@google.com, Thomas Gleixner , tkjos@google.com, Vladimir Davydov , Vlastimil Babka , Will Deacon Subject: Re: [PATCH v5 1/6] mm/page_idle: Add per-pid idle page tracking using virtual index Message-Id: <20190807135840.92b852e980a9593fe91fbf59@linux-foundation.org> In-Reply-To: <20190807204530.GB90900@google.com> References: <20190807171559.182301-1-joel@joelfernandes.org> <20190807130402.49c9ea8bf144d2f83bfeb353@linux-foundation.org> <20190807204530.GB90900@google.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, 7 Aug 2019 16:45:30 -0400 Joel Fernandes wrote: > On Wed, Aug 07, 2019 at 01:04:02PM -0700, Andrew Morton wrote: > > On Wed, 7 Aug 2019 13:15:54 -0400 "Joel Fernandes (Google)" wrote: > > > > > In Android, we are using this for the heap profiler (heapprofd) which > > > profiles and pin points code paths which allocates and leaves memory > > > idle for long periods of time. This method solves the security issue > > > with userspace learning the PFN, and while at it is also shown to yield > > > better results than the pagemap lookup, the theory being that the window > > > where the address space can change is reduced by eliminating the > > > intermediate pagemap look up stage. In virtual address indexing, the > > > process's mmap_sem is held for the duration of the access. > > > > So is heapprofd a developer-only thing? Is heapprofd included in > > end-user android loads? If not then, again, wouldn't it be better to > > make the feature Kconfigurable so that Android developers can enable it > > during development then disable it for production kernels? > > Almost all of this code is already configurable with > CONFIG_IDLE_PAGE_TRACKING. If you disable it, then all of this code gets > disabled. > > Or are you referring to something else that needs to be made configurable? Yes - the 300+ lines of code which this patchset adds! The impacted people will be those who use the existing idle-page-tracking feature but who will not use the new feature. I guess we can assume this set is small...